AP Bio Unit 5 Vocabulary

The transmission of traits from one generation to the next

The study of heredity and hereditary variation

This type of reproduction involves a single individual, has no fusion of gametes, produces offspring that are clones, and is where mutations are the only source of variation

This type of reproduction involves two parents and genetically varied offspring with many unique combinations of genes from the parents

Segments of DNA that code for basic units of heredity. Offspring acquire these from parents by inheriting chromosomes.

A pair of chromosomes with the same size, length, and centromere position that carry the same genetic information. One is from mom and one is from dad.

A display of chromosome pairs ordered by size and length

Cells that are diploid (also known as 2n)

• Body cells

Cells that are haploid (or n)

• Reproductive/sex cells

Chromosomes that do not determine sex

• Humans have 22 pairs

Chromosomes that determine sex

• X and Y

• Humans have one set

• Males have XY and females have XX

Sequence of stages in the reproductive history of an organism from conception to its own reproduction

Offspring that are exact copies of parent

2 complete sets of each chromosome

• Shown through 2n

• Ex: 2n=46

1 set of each chromosome

• Shown through n

• Ex: n=23

A process that creates haploid gamete cells in sexually reproducing diploid organisms

• Results in daughter cells with half the number of chromosomes as the parent cell

• Involves two rounds of division

A change in the usual DNA sequence at any particular section of a gene

• Can be harmful, beneficial or neutral

• The only form of genetic variation in asexual organisms

A diploid cell that results from the fusion of two haploid gametic cells

• A fertilized egg (in humans)

Organisms that produce offspring of the same variety over many generations of self pollination

True-breeding parental generation

(First filial) hybrid offspring of P generation

(Second filial) offspring of the F1 generation

Diagrams used to predict the allele combinations of offspring from a cross with known genetic compositions

• Capital letter = Dominant

• Lowercase letter = Recessive

An organism that has a pair of identical alleles for a character

• (Dominant) Ex: AA

• (Recessive) Ex: aa

An organism that has 2 different alleles for a gene

• Ex: Aa

The genetic makeup (alleles) of an organism

An organism’s appearance, which is determined by the organism’s genotype

Alternative versions of a gene

Crosses between two individual’s genotypes to find the probabilities of each possible offspring genotype (and subsequently phenotype) for one trait only.

• Ex: Aa x AA

Crosses between two individual’s genotypes to find the probabilities of each possible offspring genotype (and subsequently phenotype) for two traits.

• Ex: YYRR x YyRr

The probability that 2 or more independent events will occur together in some specific combination.

• Ex: Probability that two coin flips will result in two heads: ½ x ½ = ¼ (or a 0.2500 mathematical probability or a 25% percentage probability)

The probability that 2 or more mutually exclusive events will occur.

• Ex: Chance that rolling a dice one time will result in a 1 or a 6: 1/6 + 1/6 = 1/3 (Or a 0.3333 mathematical probability or a 33% percentage probability)

Family tree(s) that give a visual of inheritance patterns of (a) particular trait(s)

The law that states that 2 alleles for the same trait separate during gamete formation and end up in different gametes.

Law that states that 2 traits are not inherited on the same allele.

An allele of this type overrules other alleles and is the one which becomes prevalent in an offspring.

An allele of this type must have another allele of the same type in order to be prevalent. Otherwise, it will be overruled by more dominant alleles.

When neither allele is fully dominant, so the F1 generation would have a phenotype that is a mix of those of the P generation.

• Ex: Red flowers crossed with white flowers will produce pink flowers

When 2 alleles that affect phenotype are both expressed.

• Ex: Human blood types (type AB)

Genes that exist in forms with more than 2 alleles

• Ex: Human blood types (IA, IB, i [otherwise known as A, B, O])

When the phenotypic expression of a gene at one locus affects a gene at another locus.

• Ex: Coat color in some mice

The effect of 2 or more genes acting on a single phenotype.

• Ex: Height, human skin color

Genes found on the X chromosome

Genes specifically found on the Y chromosome

• Very few of these genes, which means very few disorders resulting from this

Offspring with phenotypes that are different from the parents

Genetic map that is based on recombination frequencies

Chromosomes fail to separate properly in meiosis 1 or meiosis 2

• Karyotyping can detect this

• Ex: Down Syndrome (3 copies of chromosome 21)

When various environmental factors influence gene expression, leading individuals with the same genotype to exhibit different phenotypes in different environments.

• Ex: Soil pH affecting flower color

• Ex: UV exposure increasing melanin production in skin

• Ex: Temperature changing the color of Siamese cats

A form of statistical analysis used to compare the actual results (observed) with the expected results.

• Determines if any deviations from the expected results are due to chance or error

When there is only one copy of a gene present rather than the typical 2 copies.

• Can be normal or abnormal

• Ex (normal): Male XY

The inactive X chromosome in the somatic cells of females

Homologous pairs of chromosomes (that separate during anaphase 1 of meiosis)

When homologous chromosomes pair up and physically connect to each other in prophase 1, forming a tetrad.

When chromosomes exchange genetic material during prophase 1.

• Produces recombinant chromosomes

When chromosomes are randomly oriented along the metaphase plate during metaphase 1.

• They can each orient with either the maternal or paternal chromosomes closer to a given pole.

The point of contact between homologous pairs of chromosomes

The phase in meiosis 1 only in which the cell goes through G1, S (where DNA is copied), and G2

The phase in which synapsis and crossing over occurs.

The phase in which independent orientation occurs where tetrads line up at the metaphase plate.

The phase in which pairs of homologous chromosomes separate, with sister chromatids still being attached.

The phase in which the nuclei and cytoplasm divide, with a haploid set of chromosomes then being in each daughter cell.

The phase in which spindle forms

• No crossing over

The phase in which chromosomes line up at the metaphase place

• The chromatids are unique

The phase in which sister chromatids separate and move towards opposite poles.

The phase in which 4 haploid cells are produced and nuclei reappear

• Each daughter cell is genetically unique.